The 12AX7 high impedance amplifier triode was designed specifically for audio use and has a high amplification factor of 100. Mullard, the original designers, describe the ECC83 (=12AX7) as a high μ double triode, having separate cathodes, primarily intended for use as a resistance-coupled amplifier or phase inverter.

This exhibit is a genuine English made 12AX7. The anode is formed from thin sheet and has the typical notch and lug fixing to close the anode.

The electrode system is flattened and seen end on the anode has a hole in the side.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 45 mm tall.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	a(2)	g(2)	k(2)	h	h	a(1)	g(1)	k(1)	hct

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	6.3	0.3	250	-2	1.2	62.5K	1.6

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This exhibit was last updated on 06 November 2007